I have an APR front CF splitter.

I haven't seen any larger splitters.
How can I get more front end down force?

 

Canards and a nice undertray.

 

Remount the APR to stick out more, and tie it into the chassis instead of the bumper cover - that's what I did.

APR will also build you a custom splitter in whatever shape you want, ie sticking out more. YOu can order a custom one through rallysportdirect.com

 

I've wondered if there was some "L-shaped" roll of plastic that could be riveted to the bottom of the bumper that would act as an air dam. I've seen many race cars with metal attachments but I would think Home Depot would have some sort of gardening/gutter/something platic roll that could do the trick. I always mean to look into this but never do follow through.